Led by Natalie Bennett, the party took a new seat in the South West and held on to their two existing seats in London and the South East of England.

The Greens had hoped for better, expecting to win six seat in the Parliament. The environmental party were also standing on a platform in favour of a referendum on Britain's membership of the EU.

"I think we're in a very febrile political period," Bennett told the BBC. "I think we are going to see a great deal of political change. And as we've seen in the results today the past is not necessarily a great guide to the future in terms of politics.

"What voters are very clearly saying, both those who voted in the polls and the 60% who stayed away is that we are not happy with politics as it is now. We want a different kind of politics, a different kind of economics.

"And the Green Party, since we offer that, in a way of offering hope rather than trying to make people feel fearful, that hope is going to be a very powerful message and a very great attraction to voters."

The Lib Dems "paid the price" for the decision to fight a strongly pro-European campaign, the party president Tim Farron said.

Clegg, who is facing calls from some activists including general election candidates to step down, should be praised for having the "backbone" to take an unpopular position over the EU and confront Ukip's "threat to British cultural values".